JP2009271526A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device which can improve contrast and optical efficiency by including a polarization layer having a reflecting surface and an absorbing surface between a liquid crystal layer and a back light. <P>SOLUTION: The liquid crystal display device comprises a back light, a liquid crystal layer disposed on the back light, a first polarization layer disposed between the back light and the liquid crystal layer, and a second polarization layer disposed on the side opposite to the side facing the backlight of the liquid crystal layer. A surface facing the back light of the first polarizing layer includes a reflecting surface, and the opposite side surface includes an absorbing surface. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device that improves contrast and light efficiency.

  In recent years, display devices have been rapidly replaced by portable thin flat display devices. Among flat panel display devices, liquid crystal display devices have the advantage of consuming low power, and are attracting attention as next-generation display devices. It also has the advantage of generating less electromagnetic waves harmful to the body.

  On the other hand, since the liquid crystal display device is not a self-luminous flat panel display device, a separate light source is required. A backlight is used as a separate light source. However, the light generated by the backlight is lost while being transmitted to the liquid crystal layer, and the light efficiency is not high. In particular, the optical loss is even greater because of the polarizing layer interposed between the backlight and the liquid crystal layer.

  In some cases, a reflection type polarizing plate is used in the liquid crystal display device for light efficiency. In this case, contrast is reduced by reflection of external light.

  The present invention can provide a liquid crystal display device that includes a polarizing layer having a reflection surface and an absorption surface between a liquid crystal layer and a backlight, and can improve contrast and light efficiency.

  The present invention provides a backlight, a liquid crystal layer disposed on the backlight, a first polarizing layer disposed between the backlight and the liquid crystal layer, and a surface of the liquid crystal layer facing the backlight. A liquid crystal display device including a second polarizing layer disposed on the opposite side of the first polarizing layer, a surface of the first polarizing layer facing the backlight including a reflecting surface, and an opposite surface including an absorbing surface.

  In the present invention, a reflective film disposed on the surface of the backlight opposite to the surface facing the first polarizing layer is further provided.

  In the present invention, a quarter wavelength retardation layer is further provided between the reflective film and the backlight.

  According to another aspect of the present invention, there is provided a backlight, a liquid crystal layer disposed on the backlight, a plurality of grids and an absorbing member disposed between the backlight and the liquid crystal layer. One polarizing layer, and a second polarizing layer disposed on the opposite side of the surface of the liquid crystal layer facing the backlight, and the grid of the first polarizing layer includes a metal and faces the backlight. Disclosed is a liquid crystal display device in which the absorbing member includes a dielectric material and is disposed between the liquid crystal layer and the grid.

  In this invention, the said absorption member is a form laminated | stacked on a grid with the same pattern as the said grid.

  In the present invention, the absorbing member is formed of a material containing cadmium selenide (CdSe), cadmium telluride (CdTe), or ruthenium.

  In the present invention, the absorbing member contains an organic substance.

  In the present invention, the absorbing member includes an inorganic substance.

  In the present invention, the absorbing member further includes a metal, and the metal and the dielectric material form a mixture.

  According to still another aspect of the present invention, a backlight, a liquid crystal layer disposed on the backlight, and a first polarizing layer including a plurality of grids disposed between the backlight and the liquid crystal layer And a second polarizing layer disposed on the opposite side of the surface of the liquid crystal layer facing the backlight, and the grid includes a first component including a dielectric material and a second component including a metal, The first component and the second component have a concentration gradient in the thickness direction of the grid, the content of the first component increases toward the liquid crystal layer, and the second component is the backlight. Disclosed is a liquid crystal display device in which the content increases in the direction toward the.

In the present invention, the first component is SiOx (x ≧ 1), SiNx (x ≧ 1), MgF ₂ , CaF ₂ , Al ₂ O ₃ , SnO ₂ , ITO (indium tin oxide), IZO (indium zinc oxide). ), ZnO and any one selected from the group consisting of In ₂ O ₃ .

  In the present invention, the second component is selected from the group consisting of Fe, Co, V, Ti, Al, Ag, Si, Cr, Mo, Ge, Y, Zn, Zr, W, Ta, Cu, and Pt. Including any one.

  In the present invention, the grids are patterned in stripes spaced apart at a predetermined interval.

  The present invention includes a polarizing layer having a reflection surface and an absorption surface between a liquid crystal layer and a backlight, can prevent reflection of external light, improve contrast and visibility, and improve the efficiency of the light source emitted from the backlight. The luminance of the liquid crystal display device can be improved.

1 is a schematic perspective view showing a liquid crystal display device according to an embodiment of the present invention. It is sectional drawing of the II-II line of FIG. It is drawing which expanded A of FIG. FIG. 6 is a schematic cross-sectional view showing a liquid crystal display device according to another embodiment of the present invention. It is drawing which expanded B of FIG. It is the schematic perspective view which showed only the 1st polarizing layer of FIG. It is a graph which shows the reflectance with respect to some visible rays among the materials of the 1st polarizing layer of FIG. It is a graph which shows a one part polarization extinction ratio among the materials of the 1st polarizing layer of FIG. FIG. 6 is a schematic cross-sectional view showing a liquid crystal display device according to still another embodiment of the present invention. It is drawing which expanded C of FIG. It is drawing which expanded the grid of FIG. It is the graph which illustrated in comparison the content of the 1st component according to the thickness of the grid of FIG. 10, and a 2nd component.

  Hereinafter, the configuration and operation of the present invention will be described in detail with reference to embodiments of the present invention illustrated in the accompanying drawings.

  FIG. 1 is a schematic perspective view showing a liquid crystal display device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II in FIG. FIG. 3 is an enlarged view of A of FIG.

  1 and 2, the liquid crystal display device 100 according to an embodiment of the present invention includes a backlight 300, a liquid crystal layer 260, a first polarizing layer 220, and a second polarizing layer 290.

  1 and 2, the liquid crystal display device 100 includes a liquid crystal display panel 200 and a backlight 300 that supplies light to the liquid crystal display panel 200. The liquid crystal display panel 200 is attached with a flexible printed circuit (FPC) 205 that transmits an image signal. A backlight unit 300 is disposed behind the liquid crystal display panel 200.

  The backlight 300 is supplied with power through the connection cable 305 and emits light through the front surface of the backlight 300. 1 and 2, the light emitted from the backlight 300 is indicated by arrows. The light emitted from the backlight 300 is supplied to the liquid crystal display panel 200.

  A reflective film 320 is disposed on the opposite surface of the backlight 300 to the liquid crystal layer 260. The reflective film 320 improves the light efficiency by directing the light emitted from the backlight 300 to the liquid crystal layer 260. A quarter-wave retardation layer 310 is disposed between the reflective film 320 and the backlight 300.

  Meanwhile, the liquid crystal display panel 200 includes a liquid crystal layer 260 and a first polarizing layer 220 and a second polarizing layer 290 disposed on both ends of the liquid crystal layer 260. This will be specifically described with reference to FIG. The liquid crystal display panel 200 includes a first substrate 210. The first substrate 210 is formed of a transparent substrate. The first substrate 210 may be a transparent glass material mainly composed of SiO2, or may be a transparent plastic.

  The first polarizing layer 220 is formed on the surface of the first substrate 210 facing the backlight 300. 3 which is an enlarged view of FIG. 2A shows a specific configuration of the first polarizing layer 220. FIG. The first polarizing layer 220 includes an absorption surface 221 and a reflection surface 222. Of the surfaces of the first polarizing layer 220, the surface facing the backlight 300 is the reflecting surface 222, and the opposite surface, that is, the surface facing the first substrate 210 is the absorbing surface 221.

  After the reflective material for forming the reflective surface 222 is formed, the absorbent material for forming the absorbent surface 221 is formed thereon. Next, the first polarizing layer 220 can be formed by patterning them all at once. However, the manufacturing method of the first polarizing layer 220 is not limited to this. The first polarizing layer 220 can be formed using various manufacturing methods, such as forming the first polarizing layer 220 by forming the absorbing surface 221 and then doping the surface with the substance that forms the reflecting surface 222.

A buffer layer 211 is formed on the other surface of the first substrate 210, that is, on the surface opposite to the surface on which the first polarizing layer 220 is formed. The buffer layer 211 is formed in order to ensure the smoothness of the first substrate 210 and prevent the impurity elements from flowing out. The buffer layer 211 can be formed of SiO ₂ and / or SiNx.

  An active layer 231 is formed on the buffer layer 211 in a predetermined pattern. A gate insulating film 232 is formed on the active layer 231, and a gate electrode 233 is formed on the gate insulating film 232 in a predetermined pattern. An interlayer insulating film 234 is formed on the gate electrode 233 so as to cover the gate electrode 233. After the interlayer insulating film 234 is formed, the gate insulating film 232 and the interlayer insulating film 234 are etched by a process such as dry etching to form a contact hole so that the region of the active layer 231 is exposed. A source electrode 235 and a drain electrode 236 are formed so as to be electrically connected to the active layer 231 through the contact hole. A passivation film 240 is formed so as to cover the source electrode 235 and the drain electrode 236, and a planarization film 250 is formed on the passivation film 240. The planarization film 250 and the passivation film 240 are etched to form the first electrode 255 in a predetermined pattern so as to be electrically connected to the source electrode 235 or the drain electrode 236.

  A second substrate 280 is disposed so as to face the first substrate 210. Similar to the first substrate 210, the second substrate 280 is formed of a transparent component. A liquid crystal layer 260 is disposed between the first substrate 210 and the second substrate 280. A color filter layer 285 is formed on the lower surface of the second substrate 280. A second electrode 275 is formed on the lower surface of the color filter layer 285, and a first alignment layer 271 and a second alignment layer that are aligned with the liquid crystal layer 260 are formed on the surfaces of the first electrode 255 and the second electrode 275 facing each other. 272 are formed.

  A second polarizing layer 290 is formed on the upper surface of the second substrate 280 that faces the outside. The second polarizing layer 290 functions as an absorbing polarizing layer. Therefore, a phase conversion layer can be provided. A protective film 295 is formed on the second polarizing layer 290 to prevent breakage due to externally applied force.

  A spacer 265 that partitions the liquid crystal layer 260 is formed between the color filter layer 285 and the planarization film 250.

  Although FIG. 2 illustrates a TFT-LCD, the liquid crystal display panel 200 of the present invention is not limited to this.

  The operation principle of the liquid crystal display device 100 will be briefly described. A potential difference is formed between the first electrode 255 and the second electrode 275 by an external signal controlled by the gate electrode 233, the source electrode 235, and the drain electrode 236. The arrangement of the liquid crystal layer 260 is determined by the potential difference, and the visible light supplied from the backlight 300 is blocked or transmitted by the arrangement of the liquid crystal layer 260. The transmitted light is colored while passing through the color filter layer 285 to implement an image.

  The first polarizing layer 220 of the liquid crystal display device 100 according to the embodiment of the present invention is disposed between the backlight 300 and the liquid crystal layer 260. The first polarizing layer includes an absorption surface 221 on the surface facing the liquid crystal layer 260. When the liquid crystal display device 100 is used, external light incident through the liquid crystal layer 260 reaches the first polarizing layer 220.

  At this time, reflection of external light is prevented by the absorption surface 221 of the first polarizing layer 220. As a result, the contrast of the liquid crystal display device 100 is improved. In addition, the surface of the first polarizing layer 220 facing the backlight 300 includes a reflective surface 222.

  The light emitted from the backlight 300 often has a property of spreading randomly without directionality. That is, some light travels toward the liquid crystal layer 260, but there is also light traveling in the opposite direction. If the amount of light traveling in the opposite direction to the liquid crystal layer 260 increases, the light efficiency may decrease.

  However, in the present invention, even if light emitted from the backlight 300 travels in the opposite direction to the liquid crystal layer 260, the light efficiency is not lowered because the light is reflected by the reflective film 320 and travels toward the liquid crystal layer 260.

  Specifically, if the light emitted from the backlight 300 reaches the first polarizing layer 220 while traveling toward the liquid crystal layer 260, the component in the direction of the transmission axis of the first polarizing layer 220 among the light components. Passes through the first polarizing layer 220 and travels toward the liquid crystal layer 260.

  Of the light components reaching the first polarizing layer 220, the component in the direction along the reflection axis of the first polarizing layer 220, that is, the component in the direction orthogonal to the transmission axis is reflected. The light reflected by the first polarizing layer 220 is converted into circularly polarized light that rotates in one direction while passing through the quarter-wave retardation layer 310. The circularly polarized light that rotates in one direction is reflected by the reflective film 320 and converted into circularly polarized light that rotates in the other direction. Circularly polarized light rotating in the other direction is converted to linearly polarized light in a direction orthogonal to the reflection axis of the first polarizing layer 220 while passing through the quarter-wave retardation layer 310. The linearly polarized light is the same as the transmission axis direction of the first polarizing layer 220 and passes through the first polarizing layer 220 toward the liquid crystal layer 260.

  Utilizing such a light circulation effect, the external light emitted from the backlight 210 is directed toward the liquid crystal layer 260 as much as possible to improve the light efficiency.

  In addition, the first polarizing layer 220 of the present invention has an absorption surface 221 on one surface and a reflection surface 222 on the other surface to prevent reflection of external light and improve the efficiency of the backlight. Since the surface having the absorption function and the reflection function is provided on one surface and the other surface, it is not necessary to separately install the absorption function polarization layer and the reflection function polarization layer.

  FIG. 4 is a schematic sectional view showing a liquid crystal display device according to another embodiment of the present invention, and FIG. 5 is an enlarged view of B of FIG. FIG. 6 is a schematic perspective view showing only the first polarizing layer of FIG. For convenience of explanation, the description will focus on differences from the above-described embodiment. The same reference numerals represent the same members.

  Referring to FIG. 4, the liquid crystal display device 400 according to an embodiment of the present invention includes a backlight 500, a liquid crystal layer 660, a first polarizing layer 620, and a second polarizing layer 690.

  Referring to FIG. 4, the liquid crystal display device 400 includes a liquid crystal display panel 600 and a backlight 500.

  A reflective film 520 is disposed on the opposite surface of the backlight 500 in the direction toward the liquid crystal layer 660. A quarter-wave retardation layer 510 is disposed between the reflective film 520 and the backlight 500.

  Meanwhile, the liquid crystal display panel 600 includes a liquid crystal layer 660 and a first polarizing layer 620 and a second polarizing layer 690 disposed on both ends of the liquid crystal layer 660.

  The liquid crystal display panel 600 includes a first substrate 610. The first polarizing layer 620 is formed on the surface of the first substrate 610 facing the backlight 500. FIG. 5, which is an enlarged view of a portion B in FIG. 4, shows a specific configuration of the first polarizing layer 620.

  The first polarizing layer 620 includes a plurality of grids 621 and an absorbing member 622. The grid 621 includes a metal so as to reflect light, and is disposed so as to face the backlight 500, and the absorbing member 622 is disposed so as to face the liquid crystal layer 660. Referring to FIG. 5, the absorbing member 622 is disposed between the first substrate 610 and the grid 621.

  The grid 621 has a form in which parallel conductor wires are arranged for the purpose of polarizing only specific polarized light with electromagnetic waves. Examples of the conductor forming the grid 621 include metals such as aluminum, silver, and chromium. The grid 621 has a constant interval P1 between the grids 621. The interval P1 is an important factor that determines the performance of the grid 621. If the interval P1 between the grids 621 is longer than the wavelength of the incident light, the grid 621 mainly functions as a diffraction grating rather than a polarization function. On the other hand, if the interval P1 between the grids 621 is shorter than the incident wavelength light, the grid 621 mainly performs a polarization function.

  The first polarizing layer 620 includes an absorbing member 622. Referring to FIG. 5, the absorbing member 622 is formed between the grid 621 and the first substrate 610. Although the thickness T2 of the absorbing member 622 is different from the thickness T1 of the grid 621, the absorbing member 622 can be formed in the same pattern so that the interval P2 of the absorbing member 622 is the same as the interval P1 of the grid 621. The absorbing member 622 can use a material having low reflectance.

  The absorbing member 622 can be formed of various materials. Cadmium selenide (CdSe), cadmium telluride (CdTe), ruthenium can be included. It can also include a dielectric material, and can include a mixture of a dielectric material and a metal.

  These materials have excellent properties as the absorbing member 622. Among them, graphs showing the results of measuring the characteristics of cadmium selenide (CdSe), cadmium telluride (CdTe), and ruthenium are shown in FIGS. FIG. 7 is a graph showing the reflectance of the material described above with respect to visible light, and FIG. 8 is a graph showing the polarization extinction ratio of the material described above.

  In order to obtain the results of FIGS. 7 and 8, the first polarizing layer 620 having the structure as shown in FIGS. 5 and 6 was manufactured and experimented. At this time, the period P1 of the grid 621 was 100 nm, and the width W1 was The absorption member 622 has a period P2 of 100 nm, a width W2 of 50 nm, and a thickness T2 of 100 nm.

The horizontal axis of FIG. 7 represents the wavelength band of visible light, and the vertical axis represents the reflectance. Referring to FIG. 7, in the case of aluminum, the reflectivity for visible light is a value of 50% or more for all of blue, green, and red. However, if the absorbing member 622 included in the first polarizing layer 620 according to the embodiment of the present invention is used, the visible light reflectance is reduced to about a half level as compared with the case of aluminum. Table 1 below is a table showing the exact numerical values of FIG.

  As can be seen from Table 1, CdSe, CdTe, and ruthenium all exhibit a low reflectance of 30% or less in all visible light wavelength bands.

Referring to FIG. 8, it can be seen that the extinction ratio of the absorbing member is superior to that of aluminum. The horizontal axis of FIG. 8 represents the wavelength band of visible light, and the vertical axis represents the polarization extinction ratio value. The polarization extinction ratio is a ratio of the optical power of the S wave incident when S polarized light is incident and the transmitted S wave, and the higher the value, the better the polarization performance. The following Table 2 is a table showing the accurate numerical values of FIG.

  As can be seen from Table 2, in the absorbing member 622, CdSe and CdTe represent a polarization extinction ratio value of 2 times or more compared to aluminum, and ruthenium represents a polarization extinction ratio value of 1000 times or more.

As described above, the absorbing member 622 may include a dielectric material. The absorbing member 622 can use various dielectric materials including an organic material or an inorganic material. When the absorbing member 622 is formed of an inorganic material, SiOx (x ≧ 1), SiNx (x ≧ 1), MgF ₂ , CaF ₂ , Al ₂ O ₃ , SnO ₂ , ITO, IZO, ZnO, In ₂ O ₃ , Materials such as Cr ₂ O ₃ , Ag ₂ O, TiO ₂ , Ta ₂ O ₅ , HfO ₂ , and nitride can be used.

  When the absorbing member 622 is formed of an organic material, polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET or PETE), polyamide (PA), polyester, polyvinyl chloride (PVC), polycarbonate (PC ), Acrylonitrile butadiene styrene (ABS), polyvinylidene chloride (PVDC), polytetrafluoroethylene (PTFE), polymethyl methacrylate (PMMA), polylactic acid (PLA), polyurethane (PU), etc. can be used. . Further, low molecules such as copper phthalocyanine (CuPc), N, N-di (naphthalen-1-yl) -N, N′-diphenyl-benzidine (NPB), tris-8-hydroxyquinoline aluminum (Alq3) Organic substances can also be used.

  Further, the absorbing member 622 includes a metal, and can be formed such that the metal and the dielectric material form a mixture. That is, a low reflectance member having a low reflectance and a high absorption coefficient can be formed by co-evaporating a metal and a dielectric material to form a party mixture. The metal can be a substance such as Fe, Co, V, Ti, Al, Ag, Si, Cr, Mo, Ge, Y, Zn, Zr, W, Ta, Cu, Pt. The dielectric material that forms a mixture with the metal may be an organic material, an inorganic material, or a compound of an organic material and an inorganic material.

Inorganic materials that form a mixture with metals include SiOx (x ≧ 1), SiNx (x ≧ 1), MgF ₂ , CaF ₂ , Al ₂ O ₃ , SnO ₂ , ITO, IZO (indium zinc oxide), ZnO, In ₂ O ₃ , Cr ₂ O ₃ , Ag ₂ O, TiO ₂ , Ta ₂ O ₅ , HfO ₂ , and nitride materials.

  Organic materials that are mixed with metals include polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET or PETE), polyamide (PA), polyester, polyvinyl chloride (PVC), polycarbonate (PC), It can be a polymer material such as acrylonitrile butadiene styrene (ABS), polyvinylidene chloride (PVDC), polytetrafluoroethylene (PTFE), polymethyl methacrylate (PMMA), polylactic acid (PLA), polyurethane (PU), etc. . Also used are low-molecular organic substances such as copper phthalocyanine (CuPc), N, N-di (naphthalen-1-yl) -N, N′-diphenyl-benzidine (NPB), tris-8-hydroxyquinoline aluminum (Alq3) it can. Then, the absorbing member 622 can be formed by mixing the above-described compound of an organic substance and an inorganic substance with a metal.

  The absorbing member 622 is formed on the grid 621 and covers the upper surface of the grid 621. That is, when external light is incident on the first polarizing layer 620 having such a structure, the absorbing member 622 stops the external light from being reflected on the metal grid 621. For such an effect, the width W2 of the absorbing member 622 can be the same as the width W1 of the grid 621.

  FIG. 6 illustrates the first polarizing layer 620 linearly patterned at a constant interval. In order to form such a structure, although not shown, after applying a material for forming the absorbing member 622 on the first substrate 610, a conductive material for forming the grid 621 is applied, and then, Such a structure can be easily obtained by performing patterning using a mask.

Further, after applying a material for forming the grid 621 on the backlight 500 placed underneath, the material for forming the absorbing member 622 may be applied and then patterned.

  A buffer layer 611 is formed on the other surface of the first substrate 610, that is, the surface opposite to the surface on which the first polarizing layer 620 is formed. An active layer 631 is formed in a predetermined pattern on the buffer layer 611, a gate insulating film 632 is formed on the active layer 631, and a gate electrode 633 is formed on the gate insulating film 632 in a predetermined pattern. .

  An interlayer insulating film 634 is formed over the gate electrode 633. After the interlayer insulating film 634 is formed, a contact hole is formed, and a source electrode 635 and a drain electrode 636 are formed so as to be electrically connected to the active layer 631 through the contact hole. A passivation film 640 is formed so as to cover the source electrode 635 and the drain electrode 636, and a planarization film 650 is formed on the passivation film 640. The first electrode 655 is formed in a predetermined pattern so as to be electrically connected to the source electrode 635 or the drain electrode 636.

  A second substrate 680 is disposed so as to face the first substrate 610. A liquid crystal layer 660 is disposed between the first substrate 610 and the second substrate 680. A color filter layer 685 is formed on the lower surface of the second substrate 680. A second electrode 675 is formed on the lower surface of the color filter layer 685, and a first alignment layer 671 and a second alignment layer that are aligned with the liquid crystal layer 660 are disposed on the surfaces of the first electrode 655 and the second electrode 675 facing each other. 672 are formed.

  A second polarizing layer 690 is formed on the upper surface of the second substrate 680 facing the outside. The second polarizing layer 690 functions as an absorbing polarizing layer. Therefore, a phase conversion layer can be provided. A protective film 695 is formed on the second polarizing layer 690. A spacer 665 that partitions the liquid crystal layer 660 is formed between the color filter layer 685 and the planarization film 650.

  The first polarizing layer 620 of the liquid crystal display device 400 according to the present embodiment is disposed between the backlight 500 and the liquid crystal layer 660. The first polarizing layer 620 includes an absorbing member 622 in the direction toward the liquid crystal layer 260.

  When the liquid crystal display device 400 is used, external light incident through the liquid crystal layer 660 reaches the first polarizing layer 620. At this time, reflection of external light is prevented by the absorbing member 622 of the first polarizing layer 620. As a result, the contrast of the liquid crystal display device 400 is improved.

  In addition, a grid 621 containing metal is provided in the direction of the first polarizing layer 620 toward the backlight 500. The light emitted from the backlight 500 reaches the grid 621 and is reflected, and the reflected light is reflected again by the reflective film 520, so that the light efficiency is improved and the luminance is improved.

  If the light emitted from the backlight 500 reaches the first polarizing layer 620 while traveling toward the liquid crystal layer 660, the component in the direction along the transmission axis of the first polarizing layer 620 among the light components is the first. The light passes through one polarizing layer 620 and travels toward the liquid crystal layer 660.

  Of the light components reaching the first polarizing layer 620, the component in the direction along the reflection axis of the first polarizing layer 620, that is, the component in the direction orthogonal to the transmission axis is reflected. The light reflected by the first polarizing layer 620 is converted into circularly polarized light that rotates in one direction while passing through the quarter-wave retardation layer 510. The circularly polarized light that rotates in one direction is reflected by the reflective film 520 and converted into circularly polarized light that rotates in the other direction. The circularly polarized light rotating in the other direction is converted into linearly polarized light in a direction orthogonal to the reflection axis of the first polarizing layer 620 while passing through the quarter wavelength retardation layer 510. The linearly polarized light is the same as the transmission axis direction of the first polarizing layer 620 and passes through the first polarizing layer 620 and travels toward the liquid crystal layer 660.

  Utilizing such a light circulation effect, the external light emitted from the backlight 500 is directed to the liquid crystal layer 660 as much as possible to improve the light efficiency.

  In particular, when the light emitted from the backlight 500 travels without directionality, the light efficiency is improved by condensing the light so that the emitted light is directed toward the liquid crystal layer 660 by utilizing the circulation effect of these lights. Let

  FIG. 9 is a schematic cross-sectional view showing a liquid crystal display device according to still another embodiment of the present invention, and FIG. 10 is an enlarged view of FIG. 9C. FIG. 11 is an enlarged view of the grid of FIG. 10, and FIG. 12 is a graph comparing the contents of the first component and the second component according to the thickness of the grid of FIG. 10.

  For convenience of explanation, the description will focus on the points different from the embodiment described above.

  Referring to FIG. 9, the liquid crystal display device 700 according to an embodiment of the present invention includes a backlight 900, a liquid crystal layer 860, a first polarizing layer 820, and a second polarizing layer 890.

  Referring to FIG. 9, the liquid crystal display device 700 includes a liquid crystal display panel 800 and a backlight 900.

  A reflective film 920 is disposed on the opposite surface of the backlight 900 in the direction toward the liquid crystal layer 860. A quarter-wave retardation layer 910 is disposed between the reflective film 920 and the backlight 900.

  On the other hand, the liquid crystal display panel 800 includes a liquid crystal layer 860 and a first polarizing layer 820 and a second polarizing layer 890 disposed at both ends of the liquid crystal layer 860.

  The liquid crystal display panel 800 includes a first substrate 810. A first polarizing layer 820 is formed on the surface of the first substrate 810 facing the backlight 900. A specific configuration of the first polarizing layer 820 is shown in FIG. 10, which is an enlarged view of a portion C in FIG. 9.

  The first polarizing layer 820 includes a plurality of grids 821. The grid 821 may be patterned in a stripe shape with a predetermined interval.

  The grid 821 has a constant interval P3 between the grids 821. These intervals P3 are important factors that determine the performance of the grid 821.

  If the interval P3 between the grids 821 is longer than the wavelength of incident light, the grid 821 mainly performs the function of a diffraction grating rather than a polarization function. On the other hand, if the interval P3 between the grids 821 is shorter than the incident wavelength light, the grid 821 mainly performs the polarization function.

  For use as a polarizer for visible light, the grid 621 can have a width W3 of 100 to 500 nanometers and a thickness T3 of 300 to 500 nanometers.

  The grid 821 includes a first component 821a and a second component 821b. The detailed structure for the grid 821 is illustrated in FIG. FIG. 11 is an enlarged view of the grid 821 of FIG. The first component 821a includes a dielectric material, and the second component 821b includes a metal. The content of the first component 821a increases in the direction toward the liquid crystal layer 860, and the content of the second component 821b increases in the direction toward the backlight 900.

The first component 821a can be formed of an insulating transparent material such as SiOx (x ≧ 1), SiNx (x ≧ 1), MgF ₂ , CaF ₂ , Al ₂ O ₃ , SnO ₂ . The first component 821a may be formed of a conductive transparent material such as ITO, IZO, ZnO, or In ₂ O ₃ . The second component 821b includes a metal. The second component 821b can be formed of Fe, Co, V, Ti, Al, Ag, Si, Cr, Mo, Ge, Y, Zn, Zr, W, Ta, Cu, or Pt. The first component 821 a and the second component 821 b have a concentration gradient in the thickness direction of the grid 821.

  11 and 12, the content of the first component 821a increases as the distance from the first substrate 810 increases, and the content of the second component 821b increases as the distance from the first substrate 810 increases. That is, the first component 821a is mainly distributed in a portion adjacent to the first substrate 810, and the second component 821b is mainly distributed in a portion far from the first substrate 810. External light is incident from the top of the drawing. That is, the light is incident on the first polarizing layer 820 through the liquid crystal layer 860. In the grid 821 provided in the first polarizing layer 820, the first component 821a formed of a dielectric material increases in the direction toward the external light. That is, the grid 821 gradually changes from an opaque metal to a transparent material as it goes to the first substrate 810 in the direction of the liquid crystal layer 860. As a result, interface reflection caused by the difference in refractive index is suppressed. When external light is incident on the grid 821, the external light is absorbed and reflection of the external light is prevented.

  A method such as co-evaporation can be used to form the grid 821 so that the first component 821a and the second component 821b have a concentration gradient. The grid 821 can be formed so that the content of the first component 821a and the second component 821b is inversely proportional by adjusting the deposition rate of the first component 821a and the second component 821b with time during co-evaporation.

  A buffer layer 811 is formed on the other surface of the first substrate 810, that is, on the surface opposite to the surface on which the first polarizing layer 820 is formed. An active layer 831 is formed in a predetermined pattern on the buffer layer 811, a gate insulating film 832 is formed on the active layer 831, and a gate electrode 833 is formed on the gate insulating film 832 in a predetermined pattern.

  An interlayer insulating film 834 is formed over the gate electrode 833. After the interlayer insulating film 834 is formed, a contact hole is formed, and a source electrode 835 and a drain electrode 836 are formed so as to be electrically connected to the active layer 831 through the contact hole. A passivation film 840 is formed so as to cover the source electrode 835 and the drain electrode 836, and a planarization film 850 is formed over the passivation film 840. The first electrode 855 is formed in a predetermined pattern so as to be electrically connected to the source electrode 835 or the drain electrode 836.

  A second substrate 880 is disposed so as to face the first substrate 810. A liquid crystal layer 860 is disposed between the first substrate 810 and the second substrate 880. A color filter layer 885 is formed on the lower surface of the second substrate 880. A second electrode 875 is formed on the lower surface of the color filter layer 885, and a first alignment layer 871 and a second alignment layer that are aligned with the liquid crystal layer 860 are disposed on the surfaces of the first electrode 855 and the second electrode 875 facing each other. 872 is formed.

  A second polarizing layer 890 is formed on the upper surface of the second substrate 880 facing the outside. The second polarizing layer 890 functions as an absorbing polarizing layer. Therefore, a phase conversion layer can be provided. A protective film 895 is formed on the second polarizing layer 890. A spacer 865 that partitions the liquid crystal layer 860 is formed between the color filter layer 885 and the planarization film 850.

  The first polarizing layer 820 of the liquid crystal display device 700 according to the present embodiment is disposed between the backlight 900 and the liquid crystal layer 860. The first polarizing layer 820 includes a plurality of grids 821. The grid 821 includes a first component 821a and a second component 821b.

  When the liquid crystal display device 700 is used, external light incident through the liquid crystal layer 860 reaches the first polarizing layer 820. The grid 821 of the first polarizing layer 820 gradually changes from an opaque metal to a transparent material toward the liquid crystal layer 860. Accordingly, the interface reflection caused by the difference in refractive index is suppressed, and when the external light is incident on the grid 821, the external light is absorbed to prevent the reflection of the external light. As a result, the contrast can be improved.

  The grid 821 of the first polarizing layer 820 gradually changes from a transparent material to an opaque metal as it goes in the direction toward the backlight 900. The light emitted from the backlight 900 reaches the grid 821 and is reflected, and the reflected light is reflected again by the reflective film 920, so that the light efficiency is improved by the light circulation effect and the luminance is improved.

  The light emitted from the backlight 900 often has a property of spreading randomly without directivity. That is, some light travels toward the liquid crystal layer 860, but there is also light traveling in the opposite direction. If the amount of light traveling in the opposite direction to the liquid crystal layer 860 increases, the light efficiency decreases.

  However, according to the present invention, even if light emitted from the backlight 900 travels in the opposite direction to the liquid crystal layer 860, it is reflected by the reflective film 920 and travels toward the liquid crystal layer 860, so that the light efficiency is not lowered.

  Specifically, if the light emitted from the backlight 900 reaches the first polarizing layer 820 in the middle of traveling toward the liquid crystal layer 860, the component in the direction of the transmission axis of the first polarizing layer 820 among the light components. Passes through the first polarizing layer 820 and travels toward the liquid crystal layer 860.

  Of the light components reaching the first polarizing layer 820, the component in the direction along the reflection axis of the first polarizing layer 820, that is, the component in the direction orthogonal to the transmission axis is reflected. The light reflected by the first polarizing layer 820 is converted into circularly polarized light that rotates in one direction while passing through the quarter-wave retardation layer 910. The circularly polarized light that rotates in one direction is reflected by the reflective film 920 and converted into circularly polarized light that rotates in the other direction. Circularly polarized light rotating in the other direction is converted into linearly polarized light in a direction orthogonal to the reflection axis of the first polarizing layer 820 while passing through the quarter-wave retardation layer 910. The linearly polarized light is the same as the transmission axis direction of the first polarizing layer 820 and passes through the first polarizing layer 820 and travels toward the liquid crystal layer 860.

  Utilizing these light circulation effects, the external light emitted from the backlight 900 is directed toward the liquid crystal layer 860 as much as possible to improve the light efficiency.

  In addition, the first polarizing layer 820 of the present invention is formed such that one surface has a large content of the first component 821a that can function as an absorbing surface, and the other surface has a large content of the second component 821b that can function as a reflecting surface. It prevents light reflection and improves backlight efficiency. It is not necessary to separately provide an absorbing function polarizing layer and a reflecting function polarizing layer by providing a surface that performs an absorbing function and a reflecting function on one surface and the other surface.

  Although the present invention has been described with reference to the embodiments illustrated in the drawings, the present invention is merely illustrative, and various modifications and equivalent other embodiments may be made by those skilled in the art. You will understand that. Therefore, the true technical protection scope of the present invention must be determined by the technical idea of the claims.

  The present invention is suitably used in a technical field related to a liquid crystal display device.

100, 400, 700 Liquid crystal display device 200, 600, 800 Liquid crystal display panel 205 Flexible printed circuit board 210, 610, 810 First substrate 211, 611, 811 Buffer layer 220, 620, 820 First polarizing layer 231, 631, 831 Active layers 232, 632, 832 Gate insulating films 233, 633, 833 Gate electrodes 234, 634, 834 Interlayer insulating films 235, 635, 835 Source electrodes 236, 636, 836 Drain electrodes 240, 640, 840 Passivation films 250, 650, 850 Flattened films 255, 655, 855 First electrodes 260, 660, 860 Liquid crystal layers 265, 665, 865 Spacers 271, 671, 871 First alignment layers 272, 672, 872 Second alignment layers 275, 675, 875 Second Electrodes 280, 680, 880 2 substrate 285,685,885 color filter layer 290,690,890 second polarization layer 300,500,900 backlight 305 connected cables 310,510,910 quarter-wave retardation layer 320,520,920 reflective film

Claims (17)

With backlight,
A liquid crystal layer disposed on the backlight;
A first polarizing layer disposed between the backlight and the liquid crystal layer;
A second polarizing layer disposed on the opposite side of the surface of the liquid crystal layer facing the backlight,
The surface of the first polarizing layer facing the backlight includes a reflecting surface, and the opposite surface includes an absorbing surface.   The liquid crystal display device according to claim 1, further comprising a reflective film disposed on a surface opposite to the surface facing the first polarizing layer among the surfaces of the backlight.   The liquid crystal display device according to claim 2, further comprising a ¼ wavelength phase difference layer disposed between the reflective film and the backlight. With backlight,
A liquid crystal layer disposed on the backlight;
A first polarizing layer that is disposed between the backlight and the liquid crystal layer and includes a plurality of grids and an absorbing member;
A second polarizing layer disposed on the opposite side of the surface of the liquid crystal layer facing the backlight,
The grid of the first polarizing layer includes a metal and is disposed toward the backlight, and the absorbing member includes a dielectric material and is disposed between the liquid crystal layer and the grid.   The liquid crystal display device according to claim 4, wherein the absorbing member is stacked on the grid in the same pattern as the grid.   The liquid crystal display device according to claim 4, wherein the absorbing member is formed of a material containing cadmium selenide (CdSe), cadmium telluride (CdTe), or ruthenium.   The liquid crystal display device according to claim 4, wherein the absorbing member includes an organic substance.   The liquid crystal display device according to claim 4, wherein the absorbing member includes an inorganic substance.   The liquid crystal display device according to claim 4, wherein the absorbing member further includes a metal, and the metal and the dielectric material form a mixture.   The liquid crystal display device according to claim 4, further comprising a reflective film disposed on a surface opposite to the surface facing the first polarizing layer among the surfaces of the backlight.   The liquid crystal display device according to claim 4, further comprising a ¼ wavelength phase difference layer disposed between the reflective layer and the backlight. With backlight,
A liquid crystal layer disposed on the backlight;
A first polarizing layer disposed between the backlight and the liquid crystal layer and including a plurality of grids;
A second polarizing layer disposed on the opposite side of the surface of the liquid crystal layer facing the backlight,
The grid includes a first component including a dielectric material and a second component including a metal, and the first component and the second component have a concentration gradient in a thickness direction of the grid, and the first component includes The amount increases as it goes in the direction toward the liquid crystal layer, and the content of the second component increases as it goes toward the backlight. The first component is selected from the group consisting of SiOx (x ≧ 1), SiNx (x ≧ 1), MgF ₂ , CaF ₂ , Al ₂ O ₃ , SnO ₂ , ITO, IZO, ZnO, and In ₂ O _3. The liquid crystal display device according to claim 12, comprising any one of the above.   The second component is any one selected from the group consisting of Fe, Co, V, Ti, Al, Ag, Si, Cr, Mo, Ge, Y, Zn, Zr, W, Ta, Cu, and Pt. The liquid crystal display device according to claim 12, comprising:   The liquid crystal display device according to claim 12, wherein the grid is patterned in a stripe shape with a predetermined interval.   The liquid crystal display device according to claim 12, further comprising a reflective film disposed on a surface of the backlight opposite to a surface facing the first polarizing layer.   The liquid crystal display device according to claim 12, further comprising a ¼ wavelength phase difference layer disposed between the reflective layer and the backlight.

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